LNG & the Liquefaction Process
Liquefied natural gas, or LNG, is natural gas in its liquid form. It is the cleanest burning fossil fuel as it produces less emissions and pollutants than either coal or oil.
The conversion of natural gas into liquid is achieved through refrigeration by cooling natural gas to -162°C. The resulting condensate is known as Liquefied Natural Gas (LNG). Liquefaction reduces the volume by about 600 times, making it more economical to transport between continents in specially designed LNG carriers. After a long journey across the sea, the LNG has to be converted back to gas so that it can be injected into the gas pipelines that will take it to consumers. Regasification of LNG occurs by passing the liquid through vaporisers that reheat the LNG using advanced technologies.
Some basic facts and information about LNG are as follows:
- Maintained as liquid at around (-162°C) and at atmospheric pressure
- Colourless, odourless and non-toxic
- 1/600 the volume of vaporised natural gas
- Stored and transported at atmospheric pressure
- Lighter than air and readily disperses into the atmosphere
- Visible as a vapour cloud if released
- Flammable only in concentrations of 5 percent to 15 percent
- Major hazard is as a vapour. Upon release it can combust, cause asphyxiation and burn human tissue. However, these hazards can and have been well managed in the industry
Difference between LNG & LPG
Liquefied petroleum gas (LPG) is a different chemical compound to natural gas even though they are both hydrocarbons. LPG consists of propane and butane while LNG is mostly methane. LPG is produced during the oil refining process or is extracted during the natural gas production process.